# -*- coding: UTF-8 -*-
def showMaxFactor(num):
    count = num / 2
    while count > 1:
        if (num % count == 0): break
        print 'largest factor of %d is %d' % (num, count)
        break
        count = count - 1
    else:
        print eachNum, 'is prime'


for eachNum in range(10, 21):
    showMaxFactor(eachNum)
